A popular cottage area in northwestern Ontario has become a global hot spot for a rare, but potentially deadly disease caused by a fungus in the soil.

Health officials are warning people who live or holiday in the Lake of the Woods area near Kenora to educate themselves about blastomycosis.

The acidic, moist soil in woodland areas around Kenora makes it an ideal breeding ground for microscopic, fungal spores. When people breathe in the spores, it can make them sick with blastomycosis.

The disease is estimated to have infected about 50 people per year in the region since 1990 â more than anywhere else in the world. The infection recently left a teenage boy with a hole in his skull that required reconstructive surgery.

Blastomycosis must be treated or it can gradually lead to death, but diagnosis can be difficult â in part because some people and animals don't fall sick until many months after being exposed to the fungus.

It's also hard to pin down because its symptoms can resemble those of the cold, pneumonia, skin infections or cancer.

The Kenora region has been undergoing an explosion of tourism, spurring health officials to be especially concerned about seasonal cottagers.

While local doctors have developed an expertise in the illness, tourists are often misdiagnosed when they return home, health officials warned.

Dr. John Embil, an expert in infectious diseases, said he and his colleagues are aware of "many" cases where doctors elsewhere have been baffled by blastomycosis.

"It's taken a long time for them to come up with the diagnosis because they're not familiar with this condition," Embil said.

Gerry Wilson, who runs the Lake of the Woods Property Owners Association, has organized weekly seminars to teach seasonal visitors about blastomycosis.

"I think most people in this area know someone who has had it, and if not someone who's had it, they certainly know someone whose dog has had it," Wilson said.

"Cottagers probably aren't quite as aware as people who live here full time."

Teen first thought to have a cold

One teenager, Daniel Birchard, nearly lost his life after catching blastomycosis while his family was at their cottage in the area.

His mother, Heidi Birchard, said the ordeal began in February, when Daniel was back home in Winnipeg and came down with a cold.

"He said, 'Mom, there's this lump on my head and I think that's where my headache is coming from,'" his mother recalled.

The teenager visited several doctors, but no one could figure out what was ailing him.

Then his mother recalled that Daniel and his father had done some work underneath their cottage in August 2004.

That same summer, the family's dog fell ill after nosing around in the soil and ended up losing an eye to infection. A veterinarian diagnosed blastomycosis.

The Birchards pushed doctors to test their son for blastomycosis. A month later, in May 2005, Daniel was diagnosed with blastomycosis.

But the fungus had already started eating through his skull, leaving a hole. He has to be very careful until he has reconstructive surgery, scheduled for the fall.

His mother said the teen realizes he could have died. "He's very aware at how close he came."

Manitoba to track blastomycosis cases

Health officials estimate that a few dozen people catch the infection in the region each year â but they aren't sure because cases aren't tracked.

Manitoba plans to make blastomycosis a reportable disease by 2006.

Health officials are lobbying the Ontario government put it back on the province's reportable list so they have a better idea of how big the problem is.